Stereotactic body radiotherapy to treat breast cancer oligometastases: A systematic review with meta-analysis

Adding Metastasis-Directed Therapy to Standard-of-Care Systemic Therapy for Oligometastatic Breast Cancer (EXTEND): A Multicenter, Randomized Phase 2 Trial

PURPOSE

Prior evidence suggests a progression-free survival (PFS) benefit from adding metastasis-directed therapy (MDT) to standard-of-care (SOC) systemic therapy for patients with some oligometastatic solid tumors. Randomized trials testing this hypothesis in breast cancer have yet to be published. We sought to determine whether adding MDT to SOC systemic therapy improves PFS in oligometastatic breast cancer.

METHODS AND MATERIALS

External Beam Radiation to Eliminate Nominal Metastatic Disease is a multicenter phase 2 randomized basket trial testing the addition of MDT to SOC systemic therapy in patients with ≤5 metastases (NCT03599765). Patients were randomly assigned 1:1 to MDT (definitive local treatment to all sites of disease, plus SOC systemic therapy) or to SOC systemic therapy-only. Primary endpoint was PFS, and secondary endpoints included overall survival, time to subsequent line of systemic therapy, and time to the appearance of new metastases. Exploratory analyses included quality of life and systemic immune response measures.

RESULTS

From September 2018 through July 2022, 22 and 21 patients were randomly assigned to the MDT and no-MDT arms, respectively. At a median follow-up of 24.8 months, PFS was not improved with the addition of MDT to SOC systemic therapy (median PFS 15.6 months MDT vs 24.9 months no-MDT [hazard ratio, 0.91; 95% CI, 0.34-2.48; P = .86]). Similarly, MDT did not improve overall survival, time to subsequent line of systemic therapy, or time to the appearance of new metastases (all P > .05). No significant differences were found in quality of life measures, systemic T-cell activation, or T-cell stimulatory cytokine concentration.

CONCLUSIONS

Among patients with oligometastatic breast cancer, the addition of MDT to SOC systemic therapy did not improve PFS. These findings suggest that MDT may have no systemic benefit in otherwise unselected patients with oligometastatic breast cancer, although this trial was limited by a heterogeneous and small sample size and overperformance of both treatment arms.

Patient Perspectives on the Value of Stereotactic Body Radiotherapy in the Management of Breast Cancer: The PERSPECTIVE Study

AIMS

Oligometastatic disease describes limited metastases amenable to therapy such as stereotactic body radiotherapy (SBRT). This study aims to understand which outcomes are most important to patients when considering SBRT as a treatment option. The insights gained will help inform future patient-directed trial endpoints and provide valuable guidance to clinicians supporting patients through their decision-making process.

MATERIALS AND METHODS

We conducted a qualitative study with focus groups and individual interviews. Participants were recruited using a purposive-sampling matrix accounting for age, presence of metastatic disease, and previous experience with radiotherapy. Each focus group had at least two moderators, and all interviews were digitally recorded and then transcribed. Thematic analysis was performed using NVivo version 12.

RESULTS

The study included 18 patients diagnosed with breast cancer, comprising two focus groups and four individual interviews. The median age was 54 years (range 38-74). 15/18 (83%) had prior radiotherapy experience, including 4/18 with previous SBRT experience. Three main themes were identified: 1) Participants' experience with radiotherapy; 2) patients' perceptions and considerations in relation to SBRT (including desired treatment outcomes); and 3) willingness to consider SBRT for its potential local control and durable pain control benefits, even in the absence of survival benefit. Participants prioritised extending their lives as the foremost desired outcome of SBRT, followed by quality of life. Those with prior SBRT experience were keen for repeat treatment, if available, and emphasised SBRT's minimal side effects compared to other interventions.

CONCLUSION

While extension of life was the primary desired treatment outcome of SBRT for oligometastatic breast cancer , all participants were willing to consider SBRT for its minimal side effects and potential benefits in local control and durable pain control, even in the absence of a survival benefit.

Stereotactic Ablative Radiotherapy for Bone-Only Oligometastatic Breast Cancer: On a Quest to Find the Optimum Cohort

AIMS

We aimed to evaluate the treatment outcomes and associated prognostic factors in breast cancer (BC) patients who had bone-only oligometastatic disease (OMD) and we tried to determine the subgroup that would benefit most from stereotactic ablative radiotherapy (SABR).

MATERIALS AND METHODS

We enrolled 47 patients with a total of 63 lesions with bone-only oligometastatic BC who underwent SABR for all bone lesions between July 2013 and March 2022. Cases with bone-only metastatic disease with up to 5 metastatic lesions that can be safely treated with SABR were included in this study. All statistical analyses were performed using SPSS 23.0 software (SPSS, Chicago, IL).

RESULTS

The median follow-up time was 34 months. The 2- and 5-year overall survival (OS) rates were 90% and 66%, and the progression-free survival (PFS) rates were 49% and 29%, respectively. The local control rate in the SABR-treated foci was 85%. In multivariate analysis, OMD state (genuine vs. induced), de-novo OMD state (synchronous vs. metachronous), and histology (luminal vs. HER-2 enriched) were prognostic for OS. Molecular subtype switch was observed in 21 (42%) patients, and 0% PFS was observed in 5 years in patients with phenotypic discordance. SABR was well tolerated and there were no ≥grade 4 acute or late toxicities.

CONCLUSION

Our study showed that in patients with bone-only OMD, in HER2-enriched subtypes with genuine & de-novo & synchronous OMD, SABR should be strongly considered for all metastatic foci, especially if there is phenotypic discordance in the primary tumor and metastasis.

Metastasis-directed stereotactic radiotherapy in patients with breast cancer: results of an international multicenter cohort study

Metastasis-directed therapy (MDT) for oligometastatic breast cancer (≤ 5 metastases) has shown little effect in specific scenarios of randomized trials. Therefore, we aimed to assess outcomes after metastasis-directed stereotactic radiotherapy (SRT) in various clinical scenarios. We conducted an international retrospective cohort study in thirteen centers including breast cancer patients receiving SRT to any metastatic site. Outcomes included local recurrence (LR), progression-free survival (PFS), and overall survival (OS). Cumulative incidence analysis was used for LR, Kaplan-Meier estimates for PFS and OS. Covariables included patient, disease, and SRT characteristics. We performed univariable and multivariable analyses (MVA). Among 444 patients, 751 metastases were treated with SRT. Of these, 73% were intracranial and 27% extracranial lesions. Oligometastatic disease (OMD) was present in 66% of the patients. LR after two years occurred significantly more often in intracranial (25%) versus extracranial lesions (7%). In MVA of patients with OMD treated for intracranial sites, higher performance status was significantly associated with longer PFS. Further, higher performance status, biologic subtype (HR-pos./HER2-pos.), and MDT to all sites were significantly associated with longer OS. In MVA of oligometastatic patients treated for extracranial sites, biologic subtype (HR-neg./HER2-pos.) and synchronous metastasis were associated with significantly longer PFS, whereas higher grading was associated with significantly shorter PFS. Moreover, biologic subtype (HR-neg./HER2-neg.) was associated with significantly shorter OS. In conclusion, the role of MDT for breast cancer may vary per clinical scenario. Patients with OMD treated for intracranial lesions who had MDT to all sites showed superior OS. Our results should be validated prospectively.

Meta-Analysis of Stereotactic Body Radiation ThERapy in Nonspine BONE Metastases (MASTER-BONES)

PURPOSE

The efficacy and safety of stereotactic body radiation therapy (SBRT) for patients with nonspine bone metastases remains in question. A systematic review and meta-analysis were performed to evaluate SBRT treatment outcomes in nonspine bone metastases.

METHODS AND MATERIALS

Eligible studies were retrieved from MEDLINE, Embase, Scielo, the Cochrane Library, and annual meeting proceedings through July 6, 2023. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline recommendations. Quantitative synthesis was performed using a random-effects model. Meta-regression was performed to determine correlation between clinical and treatment factors with the local failure (LF) and fracture rate. P values ≤.05 were deemed statistically significant.

RESULTS

Seven retrospective studies, with a total of 807 patients (1048 lesions) treated with SBRT were included, with median follow-up ranging from 7.6 to 26.5 months. The most common SBRT sites were pelvis (39.2%), ribs (25.8%), femur (16.7%), and humerus/shoulder region (8.7%). At 1 year, the LF and fracture rate were 7% (95% CI, 5.5%-8.5%; I2 = 0; n = 75/1048) and 5.3% (95% CI, 3%-7.5%; I2 = 0; n = 65/1010). The 2-year cumulative LF incidence was 12.1% (95% CI, 10%-15.5%). The overall survival and progression-free survival at 1 year were 82% (95% CI, 75%-88%; I2 = 82%; n = 746/867) and 33.5% (95% CI, 26%-41%; I2 = 0%; n = 51/152), with a median of 20.2 months (95% CI, 10.9-49.1 months) and 8.3 months (95% CI, 6.3-10.3 months) for overall survival and progression-free survival, respectively. Meta-regression analysis revealed a significant relationship between planning target volume and fracture rate (P < .05). Ribs (2.5%) followed by the femur (1.9%; 95% CI, 0%-6.1%) were the most common fracture sites. The occurrence of pain flare, fatigue, and dermatitis were 7%, 5.4%, and 0.65%, respectively.

CONCLUSIONS

Stereotactic body radiation proves both safety and efficacy for non-spine bone metastases, and although serious complications (grade 3) are rare, one case of grade 5 complication was reported. Careful consideration of target volume is crucial due to its link with a higher fracture risk.

Research hotspots and frontiers of neoadjuvant therapy in triple-negative breast cancer: a bibliometric analysis of publications between 2002 and 2023

Triple-negative breast cancer (TNBC) is a highly aggressive type of breast cancer with poor prognosis, and neoadjuvant therapy (NAT) has emerged as an important component in managing advanced-stage patients by providing surgical opportunities and improving survival outcomes. A search of publications on NAT for TNBC from 2002 to 2023 was conducted through the Web of Science core collection. A comprehensive bibliometric analysis was conducted on the data using CiteSpace, VOSviewer, and Bibliometrix. The analysis revealed a continuous and steady growth in the number of articles published in this field over the past 20 years. The United States has made significant contributions to this field, with The University of Texas MD Anderson Cancer Center publishing the most articles. Loibl, S. from Germany was found to be the most published author with 54 articles. Analysis of the journals showed that the Journal of Clinical Oncology is the most cited journal. Combined with the keyword co-occurrence analysis and clustering analysis, current research topic focuses on treatment regimens and disease prognosis. Dual-map overlay of the journals indicates that the research trend is gradually shifting from molecular biology and genetics to immunology and clinical research. Combination therapy, including immunotherapy, may be the future direction for NAT treatment of TNBC. Overall, this study provides valuable insights into the current research status, latest advancements, and emerging development trend of NAT for TNBC.

Cancer-specific dose and fractionation schedules in stereotactic body radiotherapy for oligometastatic disease: An interim analysis of the EORTC-ESTRO E2-RADIatE OligoCare study

BACKGROUND AND INTRODUCTION

Optimal dose and fractionation in stereotactic body radiotherapy (SBRT) for oligometastatic cancer patients remain unknown. In this interim analysis of OligoCare, we analyzed factors associated with SBRT dose and fractionation.

MATERIALS AND METHODS

Analysis was based on the first 1,099 registered patients. SBRT doses were converted to biological effective doses (BED) using α/β of 10 Gy for all primaries, and cancer-specific α/β of 10 Gy for non-small cell lung and colorectal cancer (NSCLC, CRC), 2.5 Gy for breast cancer (BC), or 1.5 Gy for prostate cancer (PC).

RESULTS

Of the interim analysis population of 1,099 patients, 999 (99.5 %) fulfilled inclusion criteria and received metastasis-directed SBRT for NSCLC (n = 195; 19.5 %), BC (n = 163; 16.3 %), CRC (n = 184; 18.4 %), or PC (n = 457; 47.5 %). Two thirds of patients were treated for single metastasis. Median number of fractions was 5 (IQR, 3-5) and median dose per fraction was 9.7 (IQR, 7.7-12.4) Gy. The most frequently treated sites were non-vertebral bone (22.8 %), lung (21.0 %), and distant lymph node metastases (19.0 %). On multivariate analysis, the dose varied significantly for primary cancer type (BC: 237.3 Gy BED, PC 300.6 Gy BED, and CRC 84.3 Gy BED), and metastatic sites, with higher doses for lung and liver lesions.

CONCLUSION

This real-world analysis suggests that SBRT doses are adjusted to the primary cancers and oligometastasis location. Future analysis will address safety and efficacy of this site- and disease-adapted SBRT fractionation approach (NCT03818503).

Stereotactic Body Radiotherapy for Extracranial Oligometastatic Disease from Head and Neck Primary Cancers: A Systematic Review and Meta-Analysis

INTRODUCTION

Stereotactic body radiotherapy (SBRT) is increasingly used to treat disease in the oligometastatic (OM) setting due to mounting evidence demonstrating its efficacy and safety. Given the low population representation in prospective studies, we performed a systematic review and meta-analysis of outcomes of HNC patients with extracranial OM disease treated with SBRT.

METHODS

A systematic review was conducted with Cochrane, Medline, and Embase databases queried from inception to August 2022 for studies with extracranial OM HNC treated with stereotactic radiotherapy. Polymetastatic patients (>five lesions), mixed-primary cohorts failing to report HNC separately, lack of treatment to all lesions, nonquantitative endpoints, and other definitive treatments (surgery, conventional radiotherapy, and radioablation) were excluded. The meta-analysis examined the pooled effects of 12- and 24-month local control (LC) per lesion, progression-free survival (PFS), and overall survival (OS). Weighted random-effects were assessed using the DerSimonian and Laird method, with heterogeneity evaluated using the I2 statistic and Cochran Qtest. Forest plots were generated for each endpoint.

RESULTS

Fifteen studies met the inclusion criteria (639 patients, 831 lesions), with twelve eligible for quantitative synthesis with common endpoints and sufficient reporting. Fourteen studies were retrospective, with a single prospective trial. Studies were small, with a median of 32 patients (range: 6-81) and 63 lesions (range: 6-126). The OM definition varied, with a maximum of two to five metastases, mixed synchronous and metachronous lesions, and a few studies including oligoprogressive lesions. The most common site of metastasis was the lung. Radiation was delivered in 1-10 fractions (20-70 Gy). The one-year LC (LC1), reported in 12 studies, was 86.9% (95% confidence interval [CI]: 79.3-91.9%). LC2 was 77.9% (95% CI: 66.4-86.3%), with heterogeneity across studies. PFS was reported in five studies, with a PFS1 of 43.0% (95% CI: 35.0-51.4%) and PFS2 of 23.9% (95% CI: 17.8-31.2%), with homogeneity across studies. OS was analyzed in nine studies, demonstrating an OS1 of 80.1% (95% CI: 74.2-85.0%) and OS2 of 60.7% (95% CI: 51.3-69.4%). Treatment was well tolerated with no reported grade 4 or 5 toxicities. Grade 3 toxicity rates were uniformly below 5% when reported.

CONCLUSIONS

SBRT offers excellent LC and promising OS, with acceptable toxicities in OM HNC. Durable PFS remains rare, highlighting the need for effective local or systemic therapies in this population. Further investigations on concurrent and adjuvant therapies are warranted.

Use of Radiotherapy in Advanced Breast Cancer: The Role of a Nurse

OBJECTIVES

Systemic therapy is the mainstay in advanced breast cancer (ABC), but innovations in radiation oncology have given radiotherapy a crucial role in the treatment of both intracranial and extracranial ABC. Breast cancer specialists include, in addition to medical and clinical oncologists, breast cancer nurses with unique theoretical knowledge and significant clinical experience. This review aims to discuss the function of radiotherapy in ABC and to highlight the role and importance of specialized nursing care for ABC patients receiving radiotherapy.

DATA SOURCES

An extensive literature review was conducted on the role of radiotherapy and its implementation in various settings of ABC and the pivotal contribution of nursing practices to the quality of life of these patients, with a particular focus on symptom and side effect management and prevention, education, as well as unmet patient needs. The Advanced Breast Cancer International Consensus Guidelines (ABC-5) were also included. All the above data were combined with the expert and practical considerations of breast cancer specialists within the team.

CONCLUSION

The sophisticated application of radiotherapy and the complexity of ABC patient management, concerning symptoms, side effects, and overall well-being necessitate collaborative efforts to optimize patient care. Breast cancer nurses hold a central role in this framework.

IMPLICATIONS FOR NURSING PRACTICE

The significance of specialized nursing in contributing to comprehensive patient care for ABC patients treated with radiotherapy outlines the need for extensive training that aims to provide a holistic approach and entails physical, mental, and emotional support and patient and caregiver education.

Effects of neoadjuvant stereotactic body radiotherapy plus adebrelimab and chemotherapy for triple-negative breast cancer: A pilot study

Background

Emerging data have supported the immunostimulatory role of radiotherapy, which could exert a synergistic effect with immune checkpoint inhibitors (ICIs). With proven effective but suboptimal effect of ICI and chemotherapy in triple-negative breast cancer (TNBC), we designed a pilot study to explore the efficacy and safety of neoadjuvant stereotactic body radiotherapy (SBRT) plus adebrelimab and chemotherapy in TNBC patients.

Methods

Treatment-naïve TNBC patients received two cycles of intravenous adebrelimab (20 mg/kg, every 3 weeks), and SBRT (24 Gy/3 f, every other day) started at the second cycle, then followed by six cycles of adebrelimab plus nab-paclitaxel (125 mg/m² on days 1 and 8) and carboplatin (area under the curve 6 mg/mL per min on day 1) every 3 weeks. The surgery was performed within 3-5 weeks after the end of neoadjuvant therapy. Primary endpoint was pathological complete response (pCR, ypT0/is ypN0). Secondary endpoints included objective response rate (ORR), residual cancer burden (RCB) 0-I, and safety.

Results

13 patients were enrolled and received at least one dose of therapy. 10 (76.9%) patients completed SBRT and were included in efficacy analysis. 90% (9/10) of patients achieved pCR, both RCB 0-I and ORR reached 100% with three patients achieved complete remission. Adverse events (AEs) of all-grade and grade 3-4 occurred in 92.3% and 53.8%, respectively. One (7.7%) patient had treatment-related serious AEs. No radiation-related dermatitis or death occurred.

Conclusions

Adding SBRT to adebrelimab and neoadjuvant chemotherapy led to a substantial proportion of pCR with acceptable toxicities, supporting further exploration of this combination in TNBC patients.

Funding

None.

Clinical trial number

NCT05132790.

Ten-Year Outcomes of Stereotactic Body Radiotherapy for Oligometastatic Breast Cancer: Does Synchronous Oligometastatic Breast Cancer Benefit?

AIMS

The benefit of stereotactic body radiotherapy (SBRT) in metachronous oligometastatic breast cancer (OMBC) has previously been described and its use in current clinical practice is established. The role of SBRT in the management of synchronous OMBC remains uncertain. The aim of this study was to compare outcomes of SBRT-treated synchronous OMBC with those of SBRT-treated metachronous OMBC.

MATERIALS AND METHODS

This was a retrospective analysis of consecutive extracranial OMBC patients treated with SBRT at a single institution between 2011 and 2022. Kaplan-Meier methods were used to calculate progression-free survival (PFS), overall survival, local control and distant control. Log-rank tests were used to test any differences. Cox regression was used for univariate and multivariate analyses to identify predictive factors. Toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE) version 5.

RESULTS

In total, 74 OMBC patients with 113 lesions were analysed. The median follow-up was 20 months (range 0-98). Seventy per cent of patients presented metachronously and 30% synchronously. 30 Gy in three fractions was most commonly prescribed, resulting in a median biologically effective dose (BED at α/β = 10) of 60 Gy (range 35.7-112.5 Gy). Forty-nine per cent of patients switched systemic therapy post-SBRT (median time to switch: 14 months, range 0-79). Two patients (2%) experienced grade 3 acute toxicities with no grade ≥4 toxicities. At 2 years overall survival was 92.4% and PFS 39.0%, local control 85.9% and distant control 37.0%. For metachronous and synchronous disease, respectively, 2-year local control rates were 86.5% and 85.8% and PFS rates were 35.3% and 48.3%. The median PFS of metachronous and synchronous disease were 18 months and 17 months, respectively (P = 0.86). Predictive factors on multivariate analysis were treated site for overall survival, change in systemic therapy post-SBRT for PFS and BED for local control.

CONCLUSION

Our data confirm SBRT as a well-tolerated treatment for OMBC with excellent local control rates regardless of metachronous or synchronous presentation. There is no suggestion that survival outcomes are inferior for synchronous disease. Further prospective studies are required to validate this finding.

Local treatment in oligometastasis from breast cancer: an overview

Oligometastasic breast cancer (OMBC) consists of breast cancer patient with a limited number of systemic metastases (≤ 5), all of them candidates for local ablative treatment with the intention of achieving long-term control of the metastasis and, eventually, an increase in survival The first consensus for the management of patients with oligometastatic breast cancer (OMBC) was published in 2007, establishing that a more aggressive multidisciplinary strategy is recommended in order to increase the survival while maintaining a good quality of life. The current scientific evidence is based on observational studies, mainly retrospective, systematic reviews and meta-analyses, and only a randomized nonexclusive study of oligometastatic (OM) published. All trials with Stereotactic Body Radiation Therapy (SBRT) in OM cancer have shown excellent tolerance and good local control, although first trials on Lung SBRT did not prove so excellent tolerance and had some deaths due to bronchus irradiation and secondary hemoptysis. There are multiple ongoing studies researching the benefit of SBRT in oligometastatic breast cancer. Despite the lack of impact on survival seen in the NRG BR-002 Trial, SBRT probably allows the delay of the systemic treatment until progression, and so, improves the quality of life of patients. We have to wait for the results of the ongoing and future studies for clarification of the role of local treatment in OMBC.

SEOM-GEICAM-SOLTI clinical guidelines in advanced breast cancer (2022)

Advanced breast cancer represents a challenge for patients and for physicians due its dynamic genomic changes yielding to a resistance to treatments. The main goal is to improve quality of live and survival of the patients through the most appropriate subsequent therapies based on the knowledge of the natural history of the disease. In these guidelines, we summarize current evidence and available therapies for the medical management of advanced breast cancer.

Designing clinical trials based on modern imaging and metastasis-directed treatments in patients with oligometastatic breast cancer: a consensus recommendation from the EORTC Imaging and Breast Cancer Groups

Breast cancer remains the most common cause of cancer death among women. Despite its considerable histological and molecular heterogeneity, those characteristics are not distinguished in most definitions of oligometastatic disease and clinical trials of oligometastatic breast cancer. After an exhaustive review of the literature covering all aspects of oligometastatic breast cancer, 35 experts from the European Organisation for Research and Treatment of Cancer Imaging and Breast Cancer Groups elaborated a Delphi questionnaire aimed at offering consensus recommendations, including oligometastatic breast cancer definition, optimal diagnostic pathways, and clinical trials required to evaluate the effect of diagnostic imaging strategies and metastasis-directed therapies. The main recommendations are the introduction of modern imaging methods in metastatic screening for an earlier diagnosis of oligometastatic breast cancer and the development of prospective trials also considering the histological and molecular complexity of breast cancer. Strategies for the randomisation of imaging methods and therapeutic approaches in different subsets of patients are also addressed.

Clinical and pathological characterization of 158 consecutive and unselected oligometastatic breast cancers in a single institution

PURPOSE

Data about incidence, biological, and clinical characteristics of oligometastatic breast cancer (OMBC) are scarce. However, these data are essential in determining optimal treatment strategy. Gaining knowledge of these elements means observing and describing large, recent, and consecutive series of OMBC in their natural history.

METHODS

We collected data retrospectively at our institution from 998 consecutive patients diagnosed and treated with synchronous or metachronous metastatic breast cancer (MBC) between January 2014 and December 2018. The only criterion used to define OMBC was the presence of one to five metastases at diagnosis.

RESULTS

Of 998 MBC, 15.8% were classified OMBC. Among these, 88% had one to three metastases, and 86.7% had only one organ involved. Bone metastases were present in 52.5% of cases, 20.9% had progression to lymph nodes, 14.6% to the liver, 13.3% to the brain, 8.2% to the lungs, and 3.8% had other metastases. 55.7% had HR+/HER2- OMBC, 25.3% had HER2+OMBC, and 19% had HR-/HER2- OMBC. The HR+/HER2- subtype statistically correlated with bone metastases (p = 0.001), the HER2+subtype with brain lesions (p = 0.001), and the HR-/HER2- subtype with lymph node metastases (p = 0.008). Visceral metastases were not statistically associated with any OMBC subtypes (p = 0.186). OMBC-SBR grade III was proportionally higher than in the ESME series of 22,109 MBC (49.4% vs. 35.1%, p < 0.001).

CONCLUSION

OMBC is a heterogeneous entity whose incidence is higher than has commonly been published. Not an indolent disease, each subgroup, with its biological and anatomical characteristics, merits specific management.

Systemic treatment with or without ablative therapies in oligometastatic breast cancer: A single institution analysis of patient outcomes

PURPOSE

Local ablative treatment (LAT) is increasingly combined with systemic therapy in oligometastatic breast cancer (OMBC), without a high-level evidence to support this strategy. We evaluated the addition of LAT to systemic treatment in terms of progression-free survival (PFS) and overall survival (OS). Secondary endpoints were local control (LC) and toxicity. We sought to identify prognostic factors associated with longer OS and PFS.

METHODS AND MATERIALS

We identified consecutive patients treated between 2014 and 2018 for synchronous or metachronous OMBC (defined as ≤ 5 metastases). LAT included stereotactic body radiation therapy (SBRT) and volumetric modulated arc therapy (VMAT), surgery, cryotherapy and percutaneous radiofrequency ablation (PRA). PFS and OS were calculated, and Cox regression models analyzed for potential predictors of survival.

RESULTS

One hundred two patients were included (no-LAT, n = 62; LAT, n = 40). Sixty-four metastases received LAT. Median follow-up was 50.4 months (95% CI [44.4; 53.4]). One patient experienced grade 3 toxicity in the LAT group. Five-year PFS and OS were 34.75% (95% CI [24.42-45.26]) and 63.21% (95% CI [50.69-73.37]) respectively. Patients receiving both LAT and systemic therapy had longer PFS and OS than those with no-LAT ([HR 0.39, p = 0.002]) and ([HR 0.31, p = 0.01]). The use of LAT, HER2-positive status and hormone-receptor positivity were associated with longer PFS and OS whereas liver metastases led to worse PFS.

CONCLUSIONS

LAT was associated with improved outcomes in OMBC when added to systemic treatment, without significantly increasing toxicity. The prognostic factors identified to extend PFS and OS may help guide clinicians in selecting patients for LAT.

Ten-year experience of bone SBRT in breast cancer: analysis of predictive factors of effectiveness

PURPOSE

Data on the benefit of stereotactic body radiation therapy (SBRT) in patients with breast cancer (BC) and bone metastases remain limited. The purpose of this study is to report our 10-year experience of bone SBRT, analyzing toxicity and prognostic factors for local control (LC); progression-free survival, and overall survival (OS).

METHODS/PATIENTS

We analyzed all spine and non-spine bone SBRT performed in patients with BC during the 2012-2022 period at our institution. Treatments carried out with ablative intent in stereotactic conditions with dose/fraction ≥ 5 Gy in 5 or fewer sessions were considered. Demographic, treatment, and toxicity data were recorded according to CTCAEv4. Risk factors were assessed through univariate and multivariate analysis by Cox regression.

RESULTS

60 bone SBRT treatments were performed during the study period. 75% were spine SBRT and 25% were non-spine SBRT (median BED₄Gy was 80 Gy₄). The median age was 52.5 years (34-79). The median tumor volume was 2.9 cm³ (0.5-39.4). The median follow-up was 32.4 months (1.2-101.7). 1 and 2 years LC were 92.9 and 86.6%, respectively. 1 and 2 years OS were 100 and 90.6%, respectively. Multivariate analysis (MVA) associated volume of the treated lesion ≥ 13 cm³ with worse LC (p = 0.046; HR 12.1, 95%CI = 1.1-140.3). In addition, deferring SBRT > 3 months after lesion diagnosis to prioritize systemic treatment showed a significant benefit, improving the 2 years LC up to 96.8% vs. 67.5% for SBRT performed before this period (p = 0.031; HR 0.1, 95%CI = 0.01-0.8). Hormonal receptors, the total number of metastases, and CA15-3 value were significantly associated with OS in MVA. During follow-up, three non-spine fractures (5%) were observed.

CONCLUSIONS

According to our data, bone SBRT is a safe and effective technique for BC. Upfront systemic treatment before SBRT offers a benefit in LC. Therefore, SBRT should be considered after prior systemic treatment in this population.

Oligometastasis in breast cancer—current status and treatment options from a radiation oncology perspective

Evidence from a few small randomized trials and retrospective cohorts mostly including various tumor entities indicates a prolongation of disease free survival (DFS) and overall survival (OS) from local ablative therapies in oligometastatic disease (OMD). However, it is still unclear which patients benefit most from this approach. We give an overview of the several aspects of stereotactic body radiotherapy (SBRT) in extracranial OMD in breast cancer from a radiation oncology perspective. A PubMed search referring to this was conducted. An attempt was made to relate the therapeutic efficacy of SBRT to various prognostic factors. Data from approximately 500 breast cancer patients treated with SBRT for OMD in mostly in small cohort studies have been published, consistently indicating high local tumor control rates and favorable progression-free (PFS) and overall survival (OS). Predictors for a good prognosis after SBRT are favorable biological subtype (hormone receptor positive, HER2 negative), solitary metastasis, bone-only metastasis, and long metastasis-free interval. However, definitive proof that SBRT in OMD breast cancer prolongs DFS or OS is lacking, since, with the exception of one small randomized trial (n = 22 in the SBRT arm), none of the cohort studies had an adequate control group. Further studies are needed to prove the benefit of SBRT in OMD breast cancer and to define adequate selection criteria. Currently, the use of local ablative SBRT should always be discussed in a multidisciplinary tumor board.

Radiotherapy and radiosensitization in breast cancer: Molecular targets and clinical applications

Relatively poor survival outcomes are observed in advanced or metastatic breast cancer, where local control of the primary or metastatic disease may be achieved by surgical resection, local ablative and radiation therapies. Radioresistance, poses a major challenge in achieving durable oncologic outcomes, mandating development of novel management strategies. Although multimodality approaches that combine radiotherapy with chemotherapy, or systemic agents, are utilized for radiosensitization and treatment of various malignancies, this approach has not yet found its clinical application in breast cancer. Some agents for breast cancer treatment can serve as radiosensitizers, creating an opportunity to enhance effects of radiation while providing systemic disease control. Hence, combination of radiotherapy with radiosensitizing agents have the potential to improve oncologic outcomes in advanced or metastatic breast cancer. This review discusses molecular targets for radiosensitization and novel systemic agents that have potential for clinical use as radiosensitizers in breast cancer.